This is a faulty dilemma. I'd ask other questions first: 

Does the "free" pump work, and work well? 
Why won't she hand-express? 
What is the risk to this mom of a poor pump or weaning to formula, which would increase her economic load which is probably the reason she's going back to work in the first place? 
Can she get access to her baby, who needs his mom as much as mom's milk? If not, why not? 
How can she afford day care if she can't afford a pump? 
Other job opportunities? 
Child support from the baby's father?
Not working for a while, even if it means receiving public assistance till her baby is older? 

Linda Smith, Dayton OH